Background
This invention relates to acoustic imaging catheters employing a rotating transducer.
It has long been recognized that acoustic imaging by use of internal probes has potential use in visualizing conditions of a body.
Wider effective use of acoustic imaging would occur, especially in the vascular system, if such a system could be considerably smaller, have good image fidelity, and be simple, inexpensive and dependable.
In a first aspect, the invention features an acoustic imaging catheter device, that has a flexible, axially elongated ultrasonic probe formed of a rotatable drive shaft with an ultrasonic transducer at its distal end, a catheter body in the form of an elongated, resinous, flexible member, and an inflatable balloon disposed on the catheter body, the catheter body having a distal portion extending distally beyond the balloon. the material of the balloon, the portion of the catheter body carrying the balloon and the distal portion of the catheter body beyond the balloon are sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. A probe receiving passage within the catheter body is constructed and arranged to rotatably slidably support the elongated ultrasonic probe at rotational speed enabling generation of acoustic images. The catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to enable axial sliding motion of the probe within the catheter body to position the transducer between at least two positions, one position located in the distal portion of the catheter, distal to the balloon, for providing an image of the wall of a body lumen in which the device is inserted to locate a region of the lumen wall requiring treatment or for viewing the lumen wall after treatment, and the other position located in the region of the catheter corresponding to the balloon, enabling viewing of the lumen wall while the balloon applies treatment conditions to the lumen wall.
In various preferred embodiments, the transducer is variably positionable in the catheter along the length of the balloon. The transducer is also positionable in a region of the catheter proximal to the balloon, the proximal region of the catheter body being sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. The transducer is variably positionable from a region of the catheter proximal to the balloon, to a region distal to the balloon.
In various preferred embodiments, the catheter device includes a position detector means adapted to detect the axial position of the transducer within the catheter body and processing means to provide an image of the body lumen as a function of the axial position and acoustic image information obtained during rotation of the transducer. The processing means includes storage means to store acoustic image information from selected axial positions of the catheter body and image reconstruction means to provide therefrom a three-dimensional image of the body lumen. The processing means is constructed and arranged to provide a three-dimensional image of the body lumen corresponding to a range of axial travel of the transducer in the catheter.
In another aspect, the invention features an acoustic imaging catheter device capable of treatment of a body lumen having a flexible axially elongated ultrasonic probe comprising a rotatable drive shaft with an ultrasonic transducer at its distal end, a catheter body in the form of an elongated, resinous, flexible member, and an inflatable treatment balloon constructed and arranged on the catheter to apply a therapeutic treatment to a portion of the human body which the balloon contacts. The material of the balloon, and the portion of the catheter body carrying the balloon are sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. A probe receiving passage within the catheter body is constructed and arranged to rotatably slidably support the elongated ultrasonic probe at rotational speed enabling generation of acoustic images. The transducer has a position within the catheter at the location of the balloon, and is arranged to form acoustic images of the portion of the body contacted by the treatment balloon during the progress of the treatment.
In various preferred embodiments, the treatment balloon is an inflatable dilatation balloon disposed on the catheter body, the wall of the balloon being comprised of non-elastomeric material resistant to substantial stretching under the dilatation pressure. The treatment balloon is associated with heating means heating inflation liquid within the balloon to controlled treatment temperature. The heating means includes electrodes connectable to a radio frequency energy source capable of heating electrically conductive liquid in the balloon on the basis of I2R losses. The catheter body has a single probe-receiving lumen constructed and arranged to slidably receive and support the elongated ultrasonic probe in a rotatable manner. The probe-receiving lumen is constructed to convey inflation fluid from a dilatation pressure source to the interior of the balloon to inflate the balloon to dilatation pressure. The catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to enable positioning of the transducer in a region of the catheter axially corresponding to the balloon for observing a region of the body simultaneously while treatment thereof is being performed by the balloon. The catheter body has a distal portion extending distally from the balloon. The distal portion of the catheter body being sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed, and the catheter body and flexible ultrasonic probe cooperatively constructed and arranged to enable axial sliding motion of the probe within the catheter body to position the transducer between at least two positions, one position located at the distal portion of the catheter, distal to the balloon, for providing an image of the wall of a body lumen in which the device is inserted to locate a region of the lumen wall requiring treatment or for viewing the lumen wall requiring treatment or for viewing the lumen wall after treatment and the other position located in the region of the catheter corresponding to the balloon, enabling viewing tissue while the balloon applies treatment conditions to the lumen wall.
In various preferred embodiments, the device further includes an inflation means comprising a screw syringe for generating dilatation pressures in the balloon. The catheter body extends through the full length of the balloon and includes a fluid port in the region of the balloon for inflating the balloon and equalization of pressure in the balloon and the catheter body. The sonolucent portion of the catheter body has a wall thickness of about 0.010 inch or less.
In various preferred embodiments, the device includes further a saddle member of limited axial extent fixed to the exterior of a portion of the catheter body corresponding to the location of the balloon. The saddle includes a lumen enabling passage of a guidewire along the exterior of the catheter body through the balloon, with portions of the guidewire proximal and distal of the balloon being exposed to the body lumen. The distal catheter extension includes a first aperture in the side wall and a second aperture, axially arranged in the distal end of the extension and the guidewire is threaded through the first and second apertures to extend distally from the device. The tubular saddle member is sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. The tubular member is formed of polyethylene.
In various preferred embodiments, the device includes a sealing member at the proximal portion of the catheter apparatus including a low friction seal in contact with the drive shaft for preventing flow of inflation fluids to distal portions of the drive shaft at dilatation pressures, while enabling rotation thereof. The drive shaft and sealing member are cooperatively constructed to enable axial motion of the transducer with respect to the catheter sheath. The sealing member includes a ball seal contacting a portion of the drive shaft and enabling rotation thereof while preventing flow of inflation fluids proximal to the ball seal. The balloon is formed of polyethylene.
In various preferred embodiments the device is sized and constructed for treatment in the vascular system. The device is sized and constructed for balloon angioplasty. The device is sized and constructed for treatment in the esophagus. The device is sized and constructed for treatment in the prostate.
In various preferred embodiments, the device further includes a self-sealing septum enabling venting of the catheter body. The septum is adapted for venting inflation fluid, provided to the catheter body in excess to prepare the catheter for use. The septum is adapted for venting air, when inflation fluid is provided to the catheter body in excess to prepare the catheter for use.
In various preferred embodiments, the entire length of the catheter body is sonolucent. The device includes means for asymmetric treatment of the vessel. The means for asymmetric treatment includes means for asymmetric heating. The asymmetric means includes multiple balloons arranged to provide asymmetric heating. The means includes an asymmetric balloon. The catheter body includes a bellows enabling extension and retraction of the body with respect to the transducer.
In another aspect, the invention also features an acoustic imaging catheter device having a flexible elongated ultrasonic probe comprising a rotatable drive shaft with an ultrasonic transducer at its distal end, a catheter body in the form of an elongated, resinous, flexible member, and an inflatable balloon disposed on the catheter body, the catheter body has a distal portion extending distally from the balloon. The distal portion of the catheter body is sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed, and a passage within the catheter body is constructed and arranged to slidably receive and support the elongated ultrasonic probe in a rotatable manner. The catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to position the probe within the catheter body to position the transducer in the sonolucent catheter extension for providing an image of the wall of a body lumen in which the device is inserted, to locate a region of the lumen wall requiring treatment or for viewing the lumen wall after treatment.
In another aspect, the invention features an acoustic imaging dilatation device having a flexible elongated ultrasonic probe comprising a rotatable drive shaft with an ultrasonic transducer at its distal end, a catheter body in the form of an elongated, resinous, flexible member capable of withstanding dilatation pressures of 100 psi or more, and an inflatable balloon disposed on the catheter body, inflatable to the dilatation pressure, and being comprised of non-elastomeric material resistant to substantial stretching under the dilatation pressure. A distal portion of the catheter body in the vicinity of the balloon is sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed, and a passage within the catheter body is constructed and arranged to receive and support the elongated ultrasonic probe in a rotatable manner. The catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to position the probe within the catheter body to position the transducer in the sonolucent catheter portion for providing an image of the wall of a body lumen in which the device is inserted.
In various preferred embodiments, the catheter body is a single lumen catheter body adapted to receive the probe and connected to a source of dilatation pressure for inflation of the balloon. The sonolucent portion of the catheter body corresponds with the location of the balloon. The sonolucent portion is a distal extension of the catheter, distal to the balloon. The catheter body extends the length of the balloon and includes a fluid port in the region of the balloon for inflation of the balloon and equalization of pressure in the balloon and catheter body.
In various embodiments, the catheter body has a distal portion extending distally from the balloon. The distal portion of the catheter body is sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed, and the catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to enable axial sliding motion of the probe within the catheter body to position the transducer between at least two positions. One position is located at the distal portion of the catheter, distal to the balloon, for providing an image of the wall of a body lumen in which the device is inserted to locate a region of the lumen wall requiring treatment or for viewing the lumen wall after treatment, and the other position is located in the region of the catheter corresponding to the balloon, enabling viewing of the lumen wall while the balloon applies treatment conditions to the lumen wall.
In another aspect, the invention features an acoustic imaging catheter device having a closed, continuous catheter body in the form of an elongated, resinous, flexible member containing therein a pressurized fluid. At least the distal portion of the catheter body is sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. A flexible elongated ultrasonic probe is provided comprising a rotatable drive shaft with an ultrasonic transducer at its distal end. The transducer has an outer diameter corresponding to the outer diameter of the drive shaft and mounted coaxially therewith. The drive shaft and transducer head forming a core that can be slidably inserted via the proximal end into the tubular body having a closed distal end to a directly, rotatably supported relationship with the body and after use can be slidably removed from the catheter body for repeated re-use in other catheter bodies. A sealing member is provided at the proximal portion of the catheter apparatus including a low friction seal in contact with the drive shaft for preventing flow of fluids to distal portions of the drive shaft, while enabling rotation thereof. The catheter body, sealing member and flexible ultrasonic probe are cooperatively constructed and arranged to enable axial sliding motion of the probe within the catheter body to position the transducer between positions in the acoustically transparent regions of the catheter body sheath for providing an image of the wall of a body lumen to locate a region requiring treatment. In pictured embodiments, a medical device is actuatable by the pressurized fluid.
In another aspect, the invention features a method for balloon dilatation. The method includes providing a balloon dilatation acoustic imaging device including a flexible elongated ultrasonic probe comprising a rotatable 25 drive shaft with an ultrasonic transducer at its distal end, a catheter body in the form of an elongated, resinous, flexible member capable of withstanding dilatation pressures of about 100 psi or more, and an inflatable balloon disposed on the catheter body. The material of the balloon and a portion of the catheter body are sonolucent and substantially matched in acoustic impedance with fluid to which the catheter is exposed. A passage within the catheter body is constructed and arranged to receive and support the elongated ultrasonic probe in a rotatable manner. The catheter and flexible ultrasonic probe are cooperatively constructed to position the transducer in the sonolucent portion of the catheter. While viewing images from the transducer, the catheter body is introduced to a body lumen having a region to be dilated, and advanced in the lumen to the region to be dilated and positioning the balloon about the region. The region is treated by balloon dilatation, and the balloon deflated. The treated region is observed to determine further treatment, and the device is removed from the body lumen.
In various preferred embodiments, the catheter body includes a distal portion extending distally from the balloon and the method includes positioning the transducer in the distal portion. The catheter balloon and the catheter body portion carrying the balloon are sonolucent, and the catheter body and flexible ultrasonic probe are cooperatively constructed and arranged to enable axial sliding motion of the probe within the catheter body to position the transducer between at least two positions, one position located in the region of the catheter corresponding to the balloon and another position located in the distal portion of the catheter, distal to the balloon, for providing an image of the wall of a body lumen in which the device is inserted to locate a region of the lumen wall requiring treatment. The probe is slid to the position distal to the balloon while advancing the catheter body to the region to be dilated, and the probe is slid to the position corresponding to the balloon during dilatation. The probe is slid to the position corresponding to the distal region after dilatation for observing the treated body lumen.
In various preferred embodiments, the balloon is constructed to enable asymmetric treatment of the body lumen and the method includes torquing the catheter body while viewing acoustic images of the lumen to properly position the balloon to effect the asymmetric treatment to a desired portion of the lumen. The apparatus further includes a self-sealing septum and the method further includes preparing the apparatus by substantially removing air from the balloon and catheter sheath. The preparing includes removing air by flushing excess fluid through the septum. The preparing includes removing air by aspirating through the septum.
In another aspect, the invention features an apparatus for detection of cancerous tumors in tissue having no natural passageway, having an elongated ultrasonic probe comprising a transducer supported on the end of an elongated rotatable drive shaft in combination with a hollow trocar adapted to receive the probe, the trocar having a side-facing sonolucent region adapted to register with the transducer while rotating, enabling the transducer to form acoustic images of tissue into which the trocar has been forced.
In various preferred embodiments, the transducer is removable from the trocar and the apparatus further includes a biopsy sampling device positionable in the trocar to sample tissue. The sampling device is a forceps. The device includes a radio-active pellet for radiation treatment of a tumor found by ultrasonic imaging.
In yet another aspect, the invention features a method for detection of cancerous tumors in tissue having no natural passageway. An elongated ultrasonic probe is provided comprising a transducer supported on the end of an elongated rotatable drive shaft in combination with a hollow trocar adapted to receive the probe, the trocar having a side-facing sonolucent region adapted to register with the transducer while rotating, enabling the transducer to form acoustic images of tissue into which the trocar has been forced, and, while observing ultrasonic images from the probe, advancing the probe into the tissue.
In preferred embodiments the probe is removable from the trocar, and the method further comprises, at the position of a tumor removing the transducer from the trocar, and introducing to the trocar a biopsy sampling means of, sampling the tumor. The biopsy sampling means is a forceps. The tissue is the liver. The tissue is the breast.
According to another aspect of the invention, an elongated, flexible ultrasonic probe of the type comprising a coil-form drive shaft and an acoustic transducer carried on the distal end of the drive shaft, is provided wherein a) the drive shaft includes at least a pair of inner and outer, concentric, oppositely and closely wound, hollow, multi-filar coils; b) each coil has a ratio of outer radius of coil to thickness of coil filament in the radial direction of between about 2xc2xd and 10; c) the coils are joined together at their respective ends with interfering contact with each other along their mutual length; and d) the filaments of each coil have a pitch angle of about 20xc2x0 or greater, so that when drive torque is applied to the drive shaft from the proximal end in the direction tending to reduce the diameter and lengthen the outer coil and increase the diameter and shorten the inner coil, a substantial component of the resultant stress on each filament of the coils is aligned with the axis of the filament, whereby substantial mechanical fidelity of angular displacement between the transducer and the proximal end of the drive shaft is maintained during rotation of the drive shaft.
According to another aspect of the invention an acoustic catheter is provided comprising an elongated, flexible, liquid-confining catheter sheath and an elongated, flexible ultrasonic probe disposed within and rotatably supported by a lumen of the sheath, the ultrasonic probe comprising a transducer supported on the end of an elongated coil-form drive shaft, the exterior of the drive shaft being supported by the internal surface of the catheter lumen, the inner diameter of the lumen being no more than about xc2xc mm greater than the outer diameter of the drive shaft along most of their mutual length and being no more than about {fraction (1/10)} mm greater than the outer diameter of the drive shaft in the distal region of the drive shaft and the transducer, a distal portion of the catheter sheath that corresponds with the position of the transducer being substantially transparent to acoustical energy transmitted and received by the transducer and the probe and the sheath being cooperatively constructed and arranged to enable removal and replacement of the sheath in a disposable manner.
According to another aspect of the invention, there is provided a catheter sheath, per se, adapted to receive and rotatably support a predetermined elongated ultrasonic probe of the type comprising a coil-form rotatable drive shaft of predetermined length and an acoustic transducer carried on the distal end of the drive shaft, the path of rotation of the transducer having a diameter no greater than the drive shaft, the catheter sheath comprising a closed-end, elongated, flexible liquid-confining, resinous, flexible member having a lumen for receiving the probe, a distal portion of the sheath corresponding to the position of the rotatable transducer when inserted in the lumen being substantially transparent to acoustical energy transmitted and received by the transducer, the internal surface of the lumen sized to rotatably support the drive shaft.
The invention also features oppositely wound coils of a flexible acoustic probe drive shaft in torsionally prestressed condition in the direction causing the outer coil to bear radially in tight contact upon the inner coil. The invention also features means at the distal end of an acoustic probe drive shaft adapted to apply dynamic drag to the rotation of the flexible shaft to enhance the mechanical fidelity of angular displacement between the proximal and distal ends of the probe.
Preferred embodiments of the invention feature the drive shaft having an outer diameter throughout its length of about 1 mm or less; a liquid-filled, relatively fixed, first sheath portion closely surrounding a segment of the distal end of the drive shaft, adapted to apply dynamic, viscous drag to the shaft during its rotation, to enhance the mechanical fidelity of angular displacement between the proximal and distal ends of the probe; the difference between the outer diameter of the shaft segment and the inner diameter of the corresponding sheath portion being in the range of about 0.05 to 0.15 mm; a second sheath portion extends a substantial distance proximally from the first sheath portion, the second sheath portion being radially spaced a greater distance from the drive shaft than the radial spacing of the first sheath portion from the shaft segment; a continuous flexible resinous sheath, of which the first sheath portion is part, encloses the transducer and drive shaft, the portion of the sheath that corresponds with the position of the transducer being substantially transparent to acoustical energy transmitted and received by the transducer; the sheath includes a catheter sheath having an outer diameter throughout its length of less than about 3 mm; the outer surface of the outer coil of the drive shaft has a liquid-pumping screw-form contour, whereby, when the drive shaft, while exposed to liquid in the sheath, is driven in the direction tending to decrease the diameter of the outer coil, the outer surface of the coil is effective to pressurize liquid distally thereof; there is fluid communication between the liquid-filled space along the drive shaft and the space occupied by the transducer, whereby the action of the screw-form contour of the shaft is effective to pressurize liquid in which the transducer is immersed; the sheath includes a catheter sheath having a distal projection supported by the catheter sheath and extending distally from the position of the transducer; the distal projection includes a catheter extension having a diameter of the order of the diameter of the catheter sheath in the region of the transducer, the projection adapted to maintain alignment of the probe with a passage of interest as the probe is moved axially for varying the view of features in the region of the passage; the distal projection includes an elongated guide means of smaller diameter and greater flexibility than the catheter sheath; the distal projection includes means to introduce contrast medium or other fluid distal of the probe; the elongated ultrasonic probe disposed within a lumen of a catheter sheath, the internal bore of the lumen serving to rotatably support the probe, a distal portion of the catheter sheath that corresponds with the position of the transducer being substantially transparent to acoustical energy transmitted and received by the transducer; and the probe and the sheath are cooperatively constructed and arranged to enable removal and replacement of the sheath in a disposable manner.
In preferred embodiments, the transducer includes a single transducer element directed at an angle to the axis of the drive shaft, and there are provided means for rotating the shaft at a speed of the order of 1800 rpm, a means for energizing the transducer to cause it to emit at a frequency in excess of about 15 MHz, position detecting means at the proximal end of the drive shaft for detecting the instantaneous angular position of the shaft to represent the instantaneous angular position of the transducer, and TV monitor means responsive to return signals from the transducer and the position detecting means for providing a display of an acoustical image based upon signals detected by the transducer.
In preferred embodiments, the portion of the catheter sheath which is substantially transparent to acoustical energy is integral (i.e., without a joint) with a proximal portion of the catheter sheath; the substantially transparent portion of the catheter sheath has a thinner wall than the proximal portion; and the catheter sheath includes a resinous substance.
Another preferred embodiment includes the elongated probe or catheter described above, in combination with a hollow trocar adapted to receive the probe or catheter, the trocar having a side-facing window adapted to register with the transducer enabling the transducer to form acoustic images of tissue into which the trocar has been forced.
Other aspects, features and advantages of the invention will be apparent from the following description of the preferred embodiments and from the claims.
The invention enables the achievement of micro-acoustic, close-up imaging, via catheter, of restricted regions of the body that are difficult of access.
One object of the invention is to improve dilatation procedures such as angioplasty by ultrasonic viewing of a body lumen to locate the region to be treated and properly position the balloon, then continuously observe the occluded region as the angioplasty procedure progresses. Finally, after treatment, the treated region of the body lumen could be inspected to determine the efficacy of the procedure. It is therefore one object of this invention to provide a dilatation catheter having an ultrasonic probe.